Transient adhesives, methods of making, and methods of use

ABSTRACT

Embodiments of the present disclosure provide for transient adhesive polymers, methods of making transient adhesive polymers, structures including the transient adhesive polymer attaching two portions of the structure to one another, and the like.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of, and claims priority to,co-pending U.S. Patent Application entitled “TRANSIENT ADHESIVES,METHODS OF MAKING, AND METHODS OF USE,” filed on Apr. 24, 2017, andassigned application Ser. No. 15/494,949, which claims the benefit ofand priority to U.S. Provisional Application entitled “POLYFORMALS FORUSE AS A TRANSIENT, CONDUCTIVE OR NON-CONDUCTIVE ADHESIVE,” filed onApr. 22, 2016, and assigned application No. 62/326,341, both of whichare incorporated herein by reference in there entireties.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under W31P4Q-14-C-0118awarded by the Defense Advanced Research Project Agency. The governmenthas certain rights in the invention.

BACKGROUND

Small electronic devices, such as sensors, are increasingly used indaily life. For example, electronic devices can be used to monitorpressure, temperature, linear acceleration and angular acceleration inautomobiles, industrial manufacturing equipment, or in wearable devices.Military personnel use sensors to monitor their own troops or to spy onothers. Sensors can detect sound, movement or the presence of largeferro-magnetic objects.

A growing problem with the ubiquitous deployment of sensors is theirpresence after they have completed their mission. In civilianapplications, the sensors occupy space in land-fills or become unwantedlitter. In military applications, the sensor can fall into enemy handsand can be reverse-engineered. Knowledge of even the presence of asensor can give an enemy valuable information about the presence andintention of a future military mission.

Beyond electronic devices, such as sensors, materials which decompose ata particular time, whether triggered by an external stimulus, naturalstimulus, or simply a timed-reaction, are of interest. Packages, packingmaterials, enclosures, wearable clothing, parachutes and other items maybe made from such decomposing materials. Decomposition of the itemseliminates the cost of retrieval and disposal, and eliminates the riskof an adversary discovering one's intentions or location. For example,parachutes are bulky to recover after use and at times, their detectionis undesirable. Simply the presence of the spent polymer item may takeup space and the component is no longer needed or wanted.

SUMMARY

Embodiments of the present disclosure provide for transient adhesivepolymers, methods of making transient adhesive polymers, structuresincluding the transient adhesive polymer attaching two portions of thestructure to one another, and the like.

In an aspect, a composition of the present disclosure, among others,includes: a transient polymer adhesive that loses its adhesiveproperties upon exposure to temperatures from about 0 to about 325° C.The transient polymer adhesive can be a thermoplastic or thermosetpolymer.

In an aspect, the thermoplastic can be represented by the followingstructure:

wherein R₁ and R_(1′) are each independently selected from C_(x)X_(y),linear or branched, where X is H or a halogen and x is 1 to 12 and y isx to 2x, and wherein R₂ and R_(2′) are each independently selected froman unsaturated cycloalkyl, wherein R₁ and R_(1′) are the same ordifferent and wherein R₂ and R_(2′) are the same or different. In anaspect, the thermoset polymer can have one of the following structures:wherein the thermoset polymer has one of the following structures:

wherein R₂ is a decomposable polymer, wherein R₁ and R₃ are eachindependently selected from C_(x)X_(y), linear or branched, where X is Hor a halogen and x is 1 to 12 and y is x to 2xy, a bivalent aryl group,a bivalent ether, a bivalent ketone, a bivalent carbonate, a bivalentamine, a bivalent amide, or a bivalent thiol, wherein R is a alkylgroup, an aryl group, an ether group, a ketone group, a carbonate group,an amine group, an amide group, or a thiol group, wherein n is 2 to100,000 and m is 2 to 100,000.

In an aspect, a structure of the present disclosure, among others,includes: a device or a textile adhered to a substrate using a transientpolymer adhesive that loses its adhesive properties upon exposure totemperatures from about 0 to about 325° C.

Other compositions, methods, features, and advantages will be or becomeapparent to one with skill in the art upon examination of the followingdrawings and detailed description. It is intended that all suchadditional compositions, methods, features and advantages be includedwithin this description, be within the scope of the present disclosure,and be protected by the accompanying claims.

DETAILED DESCRIPTION

This disclosure is not limited to particular embodiments described, andas such may, of course, vary. The terminology used herein serves thepurpose of describing particular embodiments only, and is not intendedto be limiting, since the scope of the present disclosure will belimited only by the appended claims.

Where a range of values is provided, each intervening value, to thetenth of the unit of the lower limit unless the context clearly dictatesotherwise, between the upper and lower limit of that range and any otherstated or intervening value in that stated range, is encompassed withinthe disclosure. The upper and lower limits of these smaller ranges mayindependently be included in the smaller ranges and are also encompassedwithin the disclosure, subject to any specifically excluded limit in thestated range. Where the stated range includes one or both of the limits,ranges excluding either or both of those included limits are alsoincluded in the disclosure.

As will be apparent to those of skill in the art upon reading thisdisclosure, each of the individual embodiments described and illustratedherein has discrete components and features which may be readilyseparated from or combined with the features of any of the other severalembodiments without departing from the scope or spirit of the presentdisclosure. Any recited method may be carried out in the order of eventsrecited or in any other order that is logically possible.

Embodiments of the present disclosure will employ, unless otherwiseindicated, techniques of electrochemistry, analytical chemistry, polymerchemistry, material science, and the like, which are within the skill ofthe art. Such techniques are explained fully in the literature.

Prior to describing the various embodiments, the following definitionsare provided and should be used unless otherwise indicated.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art of microbiology, molecular biology, medicinal chemistry, and/ororganic chemistry. Although methods and materials similar or equivalentto those described herein can be used in the practice or testing of thepresent disclosure, suitable methods and materials are described herein.

As used in the specification and the appended claims, the singular forms“a,” “an,” and “the” may include plural referents unless the contextclearly dictates otherwise. Thus, for example, reference to “a support”includes a plurality of supports. In this specification and in theclaims that follow, reference will be made to a number of terms thatshall be defined to have the following meanings unless a contraryintention is apparent.

Definitions:

The term “substituted” refers to any one or more hydrogens on thedesignated atom that can be replaced with a selection from the indicatedgroup, provided that the designated atom's normal valence is notexceeded, and that the substitution results in a stable compound.

As used herein, “alkyl” or “alkyl group” refers to a saturated aliphatichydrocarbon which can be straight or branched and/or substituted orunsubstituted, having 1 to 20 carbon atoms, wherein the stated range ofcarbon atoms includes each intervening integer individually, as well assub-ranges. An alkyl group can be monovalent (e.g., —CH₃) or bivalent(e.g., —CH₂—CH₂—) depending upon the specific structure or formula whichit is used. A bivalent group is one which has two carbon-carbon sigmabonds, such as a —CH₂— or methylene group (i.e., bivalent alkyl group),as compared to a terminal —CH₃ (methyl) alkyl group which has only onecarbon-carbon sigma bond. Examples of alkyl include, but are not limitedto methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, tert-butyl,n-pentyl, and sec-pentyl, and the like.

The term “cycloalkyl” refers to a non-aromatic mono-or multicyclic ringsystem of about 3 to about 10 carbon atoms, preferably of about 5 toabout 10 carbon atoms, where the cycloalkyl can be saturated orunsaturated (monovalent (—R) or bivalent (—R—)). In a particularembodiment, the cycloalkyl is unsaturated. Preferred ring sizes of ringsof the ring system include about 5 to about 6 ring atoms. Unless statedotherwise, “cycloalkyl” includes substituted and unsubstitutedcycloalkyls. Exemplary monocyclic cycloalkyl include cyclopentyl,cyclohexyl, cycloheptyl, and the like. Exemplary multicyclic cycloalkylinclude 1-decalin, norbornyl, adamant-(1- or 2-)yl, and the like.

The term “aryl” as used herein, refers to an aromatic monocyclic ormulticyclic ring system (fused rings). Unless stated otherwise, “aryl”includes substituted and unsubstituted aryls (monovalent (—R) orbivalent (—R—)). Exemplary aryl groups include phenyl or naphthyl, orphenyl substituted or naphthyl substituted.

As used herein, “halo”, “halogen”, or “halogen radical” refers to afluorine, chlorine, bromine, and iodine, and radicals thereof. Further,when used in compound words, such as “haloalkyl” or “haloalkenyl”,“halo” refers to an alkyl or alkenyl radical in which one or morehydrogens are substituted by halogen radicals. Examples of haloalkylinclude, but are not limited to, trifluoromethyl, trichloromethyl,pentafluoroethyl, and pentachloroethyl.

Transient adhesive or transient polymer adhesive is a polymeric materialwhich initially possesses adhesive properties and can be used to joincomponents together. The adhesive can be of the sticky or tacky varietywhich joins components by means of physical adhesion forces. An adhesivecan also form chemical bonds, such as covalent bonds which providechemical adhesion. The transient adhesive can be triggered so as totransform it into smaller molecular weight, non-adhesive products (e.g.,carbon dioxide, water, or hydrocarbons). The low molecular weightproducts can either be in the gaseous, liquid or solid state dependingon the temperature and chemical structure of the products. Aftertransformation, the solid can melt and the liquid can evaporate (e.g.,hydrocarbon). The transformation of the polymer adhesive directly into agas (e.g., carbon dioxide) would result in immediate vaporization of theadhesive. The triggering event can be a thermal heating, chemicalattack, chemical catalyst (i.e. trigger material is regenerated aftereach trigger event), photo-activated event, acoustic-activated event,radiation-activated event, or other stimulus which transforms thepolymer adhesive.

The transformation of the transient polymer adhesive will have an onsettemperature for the event, T_(Donset). If the temperature were rampedfrom below T_(Donset) to values above T_(Donset), such as in a thermalexperiment, the temperature at the onset of the polymer transition wouldbe identified as T_(Donset). T_(Donset(cat)) means the transformationtemperature when a catalyst participates in the reaction. A person ofordinary skill in the art would recognize that T_(Donset) is not asingle temperature value but rather a range of values because it couldchange slightly depending on the ramp rate or time spent any particulartemperature.

Discussion:

Embodiments of the present disclosure provide for transient adhesivepolymers, methods of making transient adhesive polymers, structuresincluding the transient adhesive polymer attaching two portions of thestructure to one another, and the like.

As described herein, there is a need for transient polymer adhesives tobe used in attaching (e.g., adhering) components in a structure.Embodiments of the present disclosure provide for transient adhesivepolymers that transform from a solid to a vapor at a particular time orwhen triggered. In this regard, embodiments of the present disclosureare advantageous in that use of the transient adhesive polymer mitigatesthe risk of detection (e.g., in military or covert actions) and lowerthe cost of disposal of devices such as electronic components (e.g.,sensors) or non-electronic items (e.g., parachutes).

Embodiments of the present disclosure provide for transient polymeradhesives that can serve as adhesives in devices and textile, where thetransient polymer adhesives lose their adhesive properties upon exposureto temperatures from about 0 to about 325° C. The temperatures can beachieved by acoustic, electrical, optical, thermal and/or chemicaleffects and can be triggered through acoustic, electrical, optical,thermal and/or chemical events. The transient polymer adhesivetransforms into volatile, small molecules (e.g., monomers and the like)when triggered. The resulting small molecules can be a vapor at ambienttemperature (i.e., have boiling point below ambient temperature), can bea liquid at ambient temperature (such as to be used withpoly(phthalaldehyde), or can vaporize at temperatures above ambienttemperature (such as to be used with polycarbonates). The resultingtransformation of the adhesive into a liquid (below, at or above roomtemperature) would allow evaporation within an acceptable time for theparticular application (e.g., hours to days).

Embodiments of the present disclosure include transient polymeradhesives, where upon exposure to temperatures of about 0 to about 325°C., about 80 to about 325° C., or about 25 to about 200° C., thetransient polymer adhesive loses (e.g., about 70 to 100%, about 80 to100%, about 90 to 100%, or about 95 to 100%) its adhesive propertiesupon activation of a trigger after a time frame (e.g., minutes to hoursto days), depending upon the specific formulation and the desiredoutcome. The term “adhesive” refers to a material used to attachstructures together for period of time under certain conditions rangingfrom a weak interaction (comes apart with less force) to a very stronginteraction (comes apart with more force) depending upon the specificformulation. In an embodiment, the transient polymer adhesives can be atransient thermoplastic polymer adhesive or a transient thermosetpolymer adhesive.

In an embodiment, the transient thermoplastic polymer adhesive can berepresented by the following structures:

where about 2 to 100,000 monomer units can be used to form the transientthermoplastic polymer adhesive. In an aspect, R₁ and R_(1′) are eachindependently selected from C_(x)X_(y), linear or branched, where X is Hor a halogen and x is 1 to 12 and y is x to 2x. In an embodiment, R₂ andR_(2′) are each independently selected from an unsaturated cycloalkyl.In an embodiment, R₂ and R_(2′) are each independently selected fromselected from

R₁ and R_(1′) can be the same or different and R₂ and R_(2′) can be thesame or different.

In an embodiment, the transient thermoplastic polymer adhesive can besynthesized through step-growth polymerization mechanisms. In anembodiment, the transient thermoplastic polymer adhesive can have aT_(g) of about 10 to 80° C. In an aspect, the T_(g) of the chemicalcomposition of the transient thermoplastic polymer adhesive can be tunedto suit the application where the components to be attached are heatedto just above polymer T_(g) where bonding occurs and then the componentsare cooled to a temperature below T_(g). T_(g) values from 30 to 50° C.are useful in bonding components.

In an embodiment, the transient thermoplastic polymer adhesive can havea T_(Donset) of about 80 to 325° C. In an aspect, the T_(Donset) of thechemical composition of the transient thermoplastic polymer adhesive canbe tuned to suit the application. The triggering temperature can behigher than the normal use temperature so that accidental triggeringdoes not occur, but not so high that adhesive transient temperature isburdensome or destructive to other components. In an embodiment, thetransient thermoplastic polymer adhesive can have both a T_(g) of 10 to80° C. and a T_(Donset) of about 80 to 325° C. In an aspect, theT_(Donset) values of about 80 to 180° C. are useful for epoxy-basedcomponents because the epoxy is stable within this range.

In an aspect, the transient thermoplastic polymer adhesive can include acatalyst or be exposed to a catalyst to initiate the transience of theadhesive. In an aspect, the T_(Donset(cat)) of the chemical compositionof the transient thermoplastic polymer adhesive can be tuned to suit theapplication considering the catalyst employed. In an embodiment, thetransient polymer adhesive can have a T_(Donset(cat)) of about 25 to200° C. The catalyst can be a strong acid catalyst or a strong basecatalyst. In an embodiment, the catalyst can be a strong acid (e.g.,HCl, H₂SO₄, sulfonic acids, fluorinated acids) or strong bases (e.g.,guanidines, phosphazenes, alkali hydroxides) where the transient polymeradhesive acts as a base and is destabilized by the acid catalyst. Thecatalyst can be strong Bronsted acids/bases (as given above) or Lewisacids/bases such as metal halides and boro halides. The acid or base canbe released directly onto the transient thermoplastic polymer adhesiveor generated thermally or photolytically by incorporating thermal orphoto acid or base generators into the transient thermoplastic polymeradhesive. A photo acid generator is a compound which when exposed to theappropriate wavelength electromagnetic radiation, reacts, and producesan acid. A photo base generator is a compound which when exposed to theappropriate wavelength electromagnetic radiation, reacts and produces abase. A thermal acid or base generator requires only thermal activationto produce an acid or base, respectively.

In an embodiment, the adhesive property of the transient thermoplasticpolymer adhesive can be recognized by measuring the adhesive force in apull-test. A pull-test is performed by applying the adhesive to acomponent, such as strip of flexible plastic or metal and then measuringthe force to pull the strip off a substrate. The strip is usually pulledin a direction normal to the rigid substrate so that the results can bequantified. The force to pull the strip off the substrate is reported asforce per strip width. Typical units may be Newtons (N) per millimeter(mm). In an embodiment, the transient thermoplastic polymer adhesive canhave an adhesive strength of about 0.02 to 2.0 N/mm or about 0.04 to0.30 N/mm. The adhesive properties can also be recognized by thematerial being sticky or tacky. Additional details are provided in theExamples.

In an embodiment, the transient thermoset polymer adhesive can berepresented by the following structures:

subscript “n” is 2 to 100,000 and subscript “m” is 2 to 100,000. In anembodiment, R₂ is a decomposable polymer. In an aspect, the decomposablepolymer is a polymer that breaks down into small molecules uponactivation by a trigger (e.g., electrical, optical, chemical, thermal oracoustic). After a suitable time frame (e.g., minutes to hours to daysbased on the application), depending upon the specific formulation ofthe transient polymer adhesive. The small molecule products can includethe monomer from which the decomposable polymer was synthesized from orcan be other chemical byproducts. In an embodiment, the decomposablepolymer can include a poly(aldehyde) containing material, a carbonatecontaining material, a hydroxyalkanoate containing material, a sulfonecontaining material, a carbamate containing material, or co-polymersthereof. In an embodiment, the decomposable polymer can be:

where n is 2 to 100,000. The transient thermoset polymer adhesives canbe synthesized from monomer containing epoxy or functional groups (e.g.,alkene, halide or alcohol) that can be reacted to an epoxypost-polymerization.

In an embodiment, R₁ and R₃ are each independently selected fromC_(x)X_(y), linear or branched, where X is H or a halogen and n is 1 to12, a bivalent aryl group, a bivalent ether, a bivalent ketone, abivalent carbonate, a bivalent amine, a bivalent amide, or a bivalentthiol, wherein bivalent is used to denote two bonds from the group sothat the valency of the atoms are maintained. In an aspect, R can be analkyl group, an aryl group, an ether group, a ketone group, a carbonategroup, an amine group, an amide group, or a thiol group.

A bond to the center of a ring system means that group can be attachedto any one of the carbon atoms. Also, the bond to the center of a ringsystem can mean one or more of those groups can be present, and if morethan one, each group is bonded to a different carbon atom.

In an embodiment, the transient thermoset polymer adhesive can have aT_(g) of about 0 to about 400° C. In an embodiment, the transientthermoset polymer adhesive can a T_(Donset) of about 0 to about 450° C.In an embodiment, the transient thermoset polymer adhesive can have botha T_(g) of 0 to about 400° C. and a T_(Donset) of about 0 to about 450°C.

In an aspect, the transient thermoset polymer adhesive can include acatalyst or be exposed to a catalyst. In an embodiment, the transientpolymer adhesive can have a T_(Donset(cat)) of about 25 to 200° C. Thecatalyst is a strong acid catalyst or a strong base catalyst. In anembodiment, the catalyst can be a strong acid (e.g., HCl, H₂SO₄,sulfonic acids, fluorinated acids) or strong bases (e.g., guanidines,phosphazenes, alkali hydroxides). The catalyst can be strong Bronstedacids/bases (as given above) or Lewis acids/bases such as metal halidesand boro halides. The acid or base can be released directly onto thetransient thermoset polymer adhesive or generated thermally orphotolytically by incorporating thermal or photo acid or base generatorsinto the transient thermoset polymer adhesive.

In an embodiment, the transient thermoset polymer adhesive can have anadhesive strength of about 0.02 to 200 or about 0.05 to 25 N/mm.

In an embodiment, the transient polymer adhesives (e.g., thermoset orthermoplastic) can be electrically conducting or electricallynon-conducting. Electrically conducting transient polymer adhesives canbe made by adding electrical conducting particles, such as metal, tonon-conducting transient polymer adhesives. The density of theelectrical conductors is such that particle-to-particle contact allowselectrical conduction from one edge of the transient polymer adhesivesto the other. In an embodiment, the metal particles can be selected sothat they are small and not visible to the eye.

As mentioned above, transformation of the adhesive from the solid tovapor state can be carried out by an electrical, chemical, thermal,optical process, and or acoustic process, which can be triggered by anelectrical, optical, chemical, thermal or acoustic trigger. In anaspect, the triggering sequence can be a series of events, such as anoptical trigger causing a chemical reaction where the chemical reactioncreates a catalyst for polymer decomposition. An example of such asequence is the absorption of light (i.e., light is the trigger) by achemical which results in the creation of an acid. The acid thencatalyzes the decomposition and vaporization of the adhesive. Theacid-catalyzed decomposition can occur at ambient temperature, insolution, or at an elevated temperature, depending on the adhesive, thecatalyst and the application.

A trigger such as an acoustic, electrical, optical, thermal and/orchemical event can be used to start the process by which the transientpolymer adhesive transforms into volatile, small molecules (e.g.,monomers and the like). The trigger is a way of exciting the transientpolymer adhesive so as to initiate the transition fromadhesive-to-nonadhesive state. The transformation can take minutes, tohours, to days depending upon the formulation and the desired outcome.

In an aspect, the acoustic trigger and process can include directabsorption of acoustic energy by the transient polymer adhesive orabsorption of acoustic energy by a secondary component which creates aspecies which initiates the transformation of the transient adhesive.

In an aspect, the electrical trigger and process can include directabsorption of electrical energy by the transient polymer adhesive orabsorption of electrical energy by a secondary component, such as aspark or heat-generating device, which creates a species which initiatesthe transformation of the transient adhesive.

In an aspect, the optical trigger and process can include directabsorption of optical energy by the transient polymer adhesive orabsorption of electrical energy by a secondary component, such as aphoto acid generator or photo base generator, which creates a specieswhich initiates the transformation of the transient adhesive.

In an aspect, the thermal trigger and process can include directabsorption of thermal energy by the transient polymer adhesive orabsorption of thermal energy by a secondary component, such as a thermalacid generator, which creates a species which initiates thetransformation of the transient adhesive.

In an aspect, the chemical trigger and process can include directabsorption of chemical energy by the transient polymer adhesive orabsorption of chemical energy by a secondary component which creates aspecies which initiates the transformation of the transient adhesive.

The structures that can be adhered together using embodiments of thetransient polymer adhesive can include devices and textiles. In general,the devices can include metal, plastic, leather, ceramic, and glass thatare bonded to devices such as sensors, printed wiring boards, energysources, and silicon chips. In general, the transient polymer adhesivecan be used to bond textiles together or components of the textilestogether or to bond textiles to other structures. The textiles caninclude fibers and yarns made of natural and synthetic materials.

While embodiments of the present disclosure are described in connectionwith the Examples and the corresponding text and figures, there is nointent to limit the disclosure to the embodiments in these descriptions.On the contrary, the intent is to cover all alternatives, modifications,and equivalents included within the spirit and scope of embodiments ofthe present disclosure.

EXAMPLE

1) Thermoplastic Type (pDHTN, pDHCH, p(DHTN-co-DHCH)

An example of a transient thermoplastic polymer adhesive ispoly(dihydroxy-tetralin) formal (pDHTN). The pDHTN had a number averagemolecular weight of 13500 g/mole, and a T_(g) around 77° C. The polymerwas synthesized from a step-growth polymerization with dibromomethaneand dihydroxy-tetralin with potassium hydroxide as a base.

The pDHTN is a solid at room temperature. It was dissolved into anappropriate solvent at 20 wt % polymer, drop-casted onto a siliconwafer, soft baked for an aount of time to remove the solvent, and thenhot pressed at 120° C. and 300 kPa. A standard pull test was performedon the aluminum bonded to the silicon. The average force per widthrequired to debond the aluminum (adhesive strength) was 0.06 N/mm. ThepDHTN adhesive properties likely rely on physical attractions, likehydrogen bonding and dipole-dipole interactions.

In this example, the pDHTN onset of decomposition temperature is 322°C., making it well suited for higher temperature applications. With theaid of an acid catalyst the onset of decomposition temperature was 50°C. The use of an acid catalyst can cleave the polymer backbone and causeelimination reactions to form major products of naphthalene (volatilesolid), formaldehyde (gas), and water (liquid or gas).

2) Thermoset Adhesive (epoxy-PPC)

An example of a thermoset transient adhesive polymer was made frompolypropylene carbonate (PPC). The PPC had a molecular weight of 2,000g/mole and a glass transition temperature (Tg) of 15° C. The hydroxylends of PPC were reacted with allyl chloroformate in tetrahydrofuran(THF) using pyridine as a catalyst. This terminated the PPC with anallyl functionality. The allyl ends of the PPC were chemicallytransformed into epoxide rings by reacting the allyl ends of the PPCwith MCPBA (meta chloro peroxi benzoic acid) in dichloromethane (DCM)for 24 hours. The new material is called epoxy-PPC.

The epoxy-PPC material is a viscoelastic liquid that was drop-casteddirectly onto a silicon wafer and subsequently bonded to aluminum foilusing the epoxy-PPC transient polymer adhesive. A standard pull test wasperformed on the aluminum bonded to the silicon. The average force perwidth of the aluminum strip to debond the aluminum after thermallycuring the epoxy-PPC was 0.27 N/mm adhesive strength. Theepoxy-terminated PPC provides excellent adhesion by forming chemicalbonds with the two surfaces. Other transient polymer adhesives formphysical interactions, such as hydrogen-bonds. Epoxy-PPC can also bebonded to the surface of parts at low-temperature by mixing it with ahardener, such as a diamine. The diamine activates the epoxy rings at alower temperature than the thermally activated event described above.This is particularly valuable for bonding temperature-sensitivecomponents.

The terminated epoxy ends improved the adhesive properties of the PPC.The PPC backbone can be replaced with other decomposable polymers statedin the above. In this example, the PPC backbone can be initiated todecompose through chemical (acid or base) or thermal pathways. It isknown that PPC can undergo backbone by cleavage of the chain ends. Thethermal stability of the cured, epoxy-PPC was evaluated in the thermalgravimetric analysis (TGA). The onset of decomposition temperature,T_(Donset), was 150° C. The major products of decomposition of PPC areCO₂ (gas) acetone (liquid), and propylene carbonate (liquid). Photoacid/base generators can be added to lower T_(Donset) to below 100° C.This is an example drawing of the epoxy-PPC decomposition.

Procedure for Adhesion Testing:1) Thermoplastic Type (pDHTN, pDHCH, p(DHTN-co-DHCH))

Polymers solutions were dropcasted onto silicon strips and doctor bladedfor thickness uniformity. The strips were baked to remove the solvent.Once the resulting polymer film had cooled, a piece of aluminum foil wasplaced on top and adhesive stack was pressed together between two hotmetal plates. Different samples were exposed to a range of pressuresbetween 100-600 kPa, and temperatures from the polymers T_(g) to 70° C.above its T_(g). The adhesive strength was measured according to ASTMD429 in an Instron, model 5842. The aluminum foil was pulled at a 90°angle from the silicon at a constant rate of 2±0.2 in./min. Adhesivestrength was reported as the average force required to peel the foil upacross the silicon strip, divided by the width of the silicon strip.

2) Thermoset Type (epoxy-PPC)

Polymers solutions were drop-casted onto silicon strips and doctorbladed for thickness uniformity. A piece of aluminum foil was placed ontop and adhesive stack was pressed with a pressure plate. The epoxylinkages were then cured at 100° C. for 1 hour on a hotplate. Theadhesive strength was measured according to ASTM D429 in an Instron,model 5842. The aluminum foil was pulled at a 90° angle from the siliconat a constant rate of 2±0.2 in./min. Adhesive strength was reported asthe average force required to peel the foil up across the silicon strip,divided by the width of the silicon strip.

Procedure for Determining Glass Transition Temperature (T_(g)):

Differential scanning calorimetry (DSC) was used to measure the T_(g) ofthe polymers. A small amount (5-10 mg) of dried polymer was pressedinside an aluminum pan and placed into the DSC with a temperature scanrate of 5° C./min.

Procedure for Determining Decomposition Temperature (T_(Dnonset) andT_(Dnonset(cat)):

Thermogravimetric analyzer (TGA) was used to measure the decompositionprofiles of the polymers. Dried polymer (5-20 mg) was placed on aplatinum pan in the TGA, and exposed to a temperature ramp rate of 1°C./min. The onset of the decomposition was taken as the temperaturewhere slope first changed on a plot of mass remaining vs. temperature.The same procedure can be followed when a catalyst is present(T_(Dnonset(cat))).

It should be noted that ratios, concentrations, amounts, and othernumerical data may be expressed herein in a range format. It is to beunderstood that such a range format is used for convenience and brevity,and thus, should be interpreted in a flexible manner to include not onlythe numerical values explicitly recited as the limits of the range, butalso to include all the individual numerical values or sub-rangesencompassed within that range as if each numerical value and sub-rangeis explicitly recited. To illustrate, a concentration range of “about0.1% to about 5%” should be interpreted to include not only theexplicitly recited concentration of about 0.1 wt % to about 5 wt %, butalso include individual concentrations (e.g., 1%, 2%, 3%, and 4%) andthe sub-ranges (e.g., 0.5%, 1.1%, 2.2%, 3.3%, and 4.4%) within theindicated range. In an embodiment, the term “about” can includetraditional rounding according to significant figures of the numericalvalue. In an embodiment, “about” as used in conjunction with zero (0)means that values plus or minus zero (0) are included (e.g., −0.9, −1,0.5, 1, etc.). In addition, the phrase “about ‘x’ to ‘y’” includes“about ‘x’ to about ‘y’”.

Many variations and modifications may be made to the above-describedembodiments. All such modifications and variations are intended to beincluded herein within the scope of this disclosure and protected by thefollowing claims.

We claim:
 1. A composition, comprising: a transient polymer adhesivethat loses its adhesive properties upon exposure to temperatures fromabout 0 to about 325° C., wherein the transient polymer adhesive is athermoset polymer, wherein the thermoset polymer has one of thefollowing structures:

wherein R₁ and R₃ are each independently selected from C_(x)X_(y),linear or branched, where X is H or a halogen and x is 1 to 12 and y isx to 2x, a bivalent aryl group, a bivalent ether, a bivalent ketone, abivalent carbonate, a bivalent amine, a bivalent amide, or a bivalentthiol, wherein R is a alkyl group, an aryl group, an ether group, aketone group, a carbonate group, an amine group, an amide group, or athiol group, wherein n is 2 to 100,000 and m is 2 to 100,000.
 2. Thecomposition of claim 1, wherein the transient polymer adhesive has aT_(g) of about 0 to about 400° C., and wherein the transient polymeradhesive has a T_(Donset) of about 0 to about 450° C. or wherein thetransient polymer adhesive further comprising a catalyst and has aT_(Donset(cat)) of about 25 to about 250° C.
 3. The composition of claim1, wherein the transient polymer adhesive loses its adhesive propertiesupon exposure to temperatures from about 80 to about 325° C.
 4. Thecomposition of claim 1, wherein the transient polymer adhesive loses itsadhesive properties upon exposure to temperatures from about 25 to about200° C.
 5. A structure, comprising: a device or a textile adhered to asubstrate using a transient polymer adhesive that loses its adhesiveproperties upon exposure to temperatures from about 0 to about 325° C.,wherein the transient polymer adhesive is a thermoset polymer, whereinthe thermoset polymer has one of the following structures:

wherein R₁ and R₃ are each independently selected from C_(x)X_(y),linear or branched, where X is H or a halogen and x is 1 to 12 and y isx to 2x, a bivalent aryl group, a bivalent ether, a bivalent ketone, abivalent carbonate, a bivalent amine, a bivalent amide, or a bivalentthiol, wherein R is a alkyl group, an aryl group, an ether group, aketone group, a carbonate group, an amine group, an amide group, or athiol group, wherein n is 2 to 100,000 and m is 2 to 100,000.
 6. Thestructure of claim 5, wherein the transient polymer adhesive has a T_(g)of about 0 to about 400° C., wherein the transient polymer adhesive hasa T_(Donset) of about 0 to about 450° C., or wherein the transientpolymer adhesive further comprising a catalyst and has a T_(Donset(cat))of about 25 to about 250° C.
 7. The structure of claim 5, wherein thetransient polymer adhesive loses its adhesive properties upon exposureto temperatures from about 80 to about 325° C.
 8. The structure of claim5, wherein the transient polymer adhesive loses its adhesive propertiesupon exposure to temperatures from about 25 to about 200° C.
 9. Astructure, comprising: a device or a textile adhered to a substrateusing a transient polymer adhesive that loses its adhesive propertiesupon exposure to temperatures from about 0 to about 325° C., wherein thetransient polymer adhesive is a thermoset polymer, wherein the thermosetpolymer has one of the following structures:

wherein R₁ and R₃ are each independently selected from a bivalent arylgroup, a bivalent ether, a bivalent ketone, a bivalent carbonate, abivalent amine, a bivalent amide, or a bivalent thiol, wherein R is aalkyl group, an aryl group, an ether group, a ketone group, a carbonategroup, an amine group, an amide group, or a thiol group, wherein n is 2to 100,000 and m is 2 to 100,000.
 10. The structure of claim 9, whereinthe transient polymer adhesive has a T_(g) of about 0 to about 400° C.,wherein the transient polymer adhesive has a T_(Donset) of about 0 toabout 450° C., or wherein the transient polymer adhesive furthercomprising a catalyst and has a T_(Donset(cat)) of about 25 to about250° C.
 11. The structure of claim 9, wherein the transient polymeradhesive loses its adhesive properties upon exposure to temperaturesfrom about 80 to about 325° C.
 12. The structure of claim 9, wherein thetransient polymer adhesive loses its adhesive properties upon exposureto temperatures from about 25 to about 200° C.
 13. A structure,comprising: a device or a textile adhered to a substrate using atransient polymer adhesive that loses its adhesive properties uponexposure to temperatures from about 0 to about 325° C., wherein thetransient polymer adhesive is a thermoset polymer, wherein the thermosetpolymer has one of the following structures:

wherein R₁ and R₃ are each independently selected from C_(x)X_(y),linear or branched, where X is H or a halogen and x is 1 to 12 and y isx to 2x, a bivalent aryl group, a bivalent ether, a bivalent ketone, abivalent carbonate, a bivalent amine, a bivalent amide, or a bivalentthiol, wherein R is a alkyl group, an aryl group, an ether group, aketone group, a carbonate group, an amine group, an amide group, or athiol group, wherein n is 2 to 100,000 and m is 2 to 100,000.
 14. Thestructure of claim 13, wherein the transient polymer adhesive has aT_(g) of about 0 to about 400° C., wherein the transient polymeradhesive has a T_(Donset) of about 0 to about 450° C., or wherein thetransient polymer adhesive further comprising a catalyst and has aT_(Donset(cat)) of about 25 to about 250° C.
 15. The structure of claim13, wherein the transient polymer adhesive loses its adhesive propertiesupon exposure to temperatures from about 80 to about 325° C.
 16. Thestructure of claim 13, wherein the transient polymer adhesive loses itsadhesive properties upon exposure to temperatures from about 25 to about200° C.